Generally, if a person works while seated on his or her chair in a fixed posture for long periods, the supply of blood and nutrients to the intervertebral disk is blocked. Thus, as time passes, the intervertebral disk becomes stiffened. Particularly, a bad posture leads to an abnormal spinal line, and causes the kyphosis that is a rearward curved line. If the kyphosis continues, the intervertebral disk of the spine compresses spinal nerves, thus causing back pain.
Therefore, a user sitting in a chair needs to frequently bend his or her back backwards and provide proper movement to the spine in order to ease the strain of the intervertebral disk and surrounding muscles and to supply blood and nutrients. Thereby, a chair having a tilting function has been disclosed, which is constructed so that the chair is tilted according to the user's movement.
As shown in FIG. 1, a conventional chair having a tilting device is provided with a mounting member 4 on which a seat plate 2 is mounted. The mounting member 4 is connected to a tilt 8 via a hinge shaft 6. The tilt 8 is connected to a leg 10. A back plate connector 14 and a lever 16 are coupled to the tilt 8. Here, the back plate connector is connected to a back plate 12, and the lever adjusts the tilting angle of the back plate. Further, an armrest 18 is coupled to a central part of each side edge of the seat plate 2 so as to support a user's arm.